drivers/platform/x86/dell-smo8800.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  dell-smo8800.c - Dell Latitude ACPI SMO88XX freefall sensor driver
   4  *
   5  *  Copyright (C) 2012 Sonal Santan <sonal.santan@gmail.com>
   6  *  Copyright (C) 2014 Pali Rohár <pali@kernel.org>
   7  *
   8  *  This is loosely based on lis3lv02d driver.
   9  */
  10
  11 #define DRIVER_NAME "smo8800"
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/acpi.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/fs.h>
  20
  21 struct smo8800_device {
  22         u32 irq;                     /* acpi device irq */
  23         atomic_t counter;            /* count after last read */
  24         struct miscdevice miscdev;   /* for /dev/freefall */
  25         unsigned long misc_opened;   /* whether the device is open */
  26         wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
  27         struct device *dev;          /* acpi device */
  28 };
  29
  30 static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
  31 {
  32         struct smo8800_device *smo8800 = data;
  33
  34         atomic_inc(&smo8800->counter);
  35         wake_up_interruptible(&smo8800->misc_wait);
  36         return IRQ_WAKE_THREAD;
  37 }
  38
  39 static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
  40 {
  41         struct smo8800_device *smo8800 = data;
  42
  43         dev_info(smo8800->dev, "detected free fall\n");
  44         return IRQ_HANDLED;
  45 }
  46
  47 static acpi_status smo8800_get_resource(struct acpi_resource *resource,
  48                                         void *context)
  49 {
  50         struct acpi_resource_extended_irq *irq;
  51
  52         if (resource->type != ACPI_RESOURCE_TYPE_EXTENDED_IRQ)
  53                 return AE_OK;
  54
  55         irq = &resource->data.extended_irq;
  56         if (!irq || !irq->interrupt_count)
  57                 return AE_OK;
  58
  59         *((u32 *)context) = irq->interrupts[0];
  60         return AE_CTRL_TERMINATE;
  61 }
  62
  63 static u32 smo8800_get_irq(struct acpi_device *device)
  64 {
  65         u32 irq = 0;
  66         acpi_status status;
  67
  68         status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
  69                                      smo8800_get_resource, &irq);
  70         if (ACPI_FAILURE(status)) {
  71                 dev_err(&device->dev, "acpi_walk_resources failed\n");
  72                 return 0;
  73         }
  74
  75         return irq;
  76 }
  77
  78 static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
  79                                  size_t count, loff_t *pos)
  80 {
  81         struct smo8800_device *smo8800 = container_of(file->private_data,
  82                                          struct smo8800_device, miscdev);
  83
  84         u32 data = 0;
  85         unsigned char byte_data;
  86         ssize_t retval = 1;
  87
  88         if (count < 1)
  89                 return -EINVAL;
  90
  91         atomic_set(&smo8800->counter, 0);
  92         retval = wait_event_interruptible(smo8800->misc_wait,
  93                                 (data = atomic_xchg(&smo8800->counter, 0)));
  94
  95         if (retval)
  96                 return retval;
  97
  98         retval = 1;
  99
 100         if (data < 255)
 101                 byte_data = data;
 102         else
 103                 byte_data = 255;
 104
 105         if (put_user(byte_data, buf))
 106                 retval = -EFAULT;
 107
 108         return retval;
 109 }
 110
 111 static int smo8800_misc_open(struct inode *inode, struct file *file)
 112 {
 113         struct smo8800_device *smo8800 = container_of(file->private_data,
 114                                          struct smo8800_device, miscdev);
 115
 116         if (test_and_set_bit(0, &smo8800->misc_opened))
 117                 return -EBUSY; /* already open */
 118
 119         atomic_set(&smo8800->counter, 0);
 120         return 0;
 121 }
 122
 123 static int smo8800_misc_release(struct inode *inode, struct file *file)
 124 {
 125         struct smo8800_device *smo8800 = container_of(file->private_data,
 126                                          struct smo8800_device, miscdev);
 127
 128         clear_bit(0, &smo8800->misc_opened); /* release the device */
 129         return 0;
 130 }
 131
 132 static const struct file_operations smo8800_misc_fops = {
 133         .owner = THIS_MODULE,
 134         .read = smo8800_misc_read,
 135         .open = smo8800_misc_open,
 136         .release = smo8800_misc_release,
 137 };
 138
 139 static int smo8800_add(struct acpi_device *device)
 140 {
 141         int err;
 142         struct smo8800_device *smo8800;
 143
 144         smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
 145         if (!smo8800) {
 146                 dev_err(&device->dev, "failed to allocate device data\n");
 147                 return -ENOMEM;
 148         }
 149
 150         smo8800->dev = &device->dev;
 151         smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
 152         smo8800->miscdev.name = "freefall";
 153         smo8800->miscdev.fops = &smo8800_misc_fops;
 154
 155         init_waitqueue_head(&smo8800->misc_wait);
 156
 157         err = misc_register(&smo8800->miscdev);
 158         if (err) {
 159                 dev_err(&device->dev, "failed to register misc dev: %d\n", err);
 160                 return err;
 161         }
 162
 163         device->driver_data = smo8800;
 164
 165         smo8800->irq = smo8800_get_irq(device);
 166         if (!smo8800->irq) {
 167                 dev_err(&device->dev, "failed to obtain IRQ\n");
 168                 err = -EINVAL;
 169                 goto error;
 170         }
 171
 172         err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
 173                                    smo8800_interrupt_thread,
 174                                    IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 175                                    DRIVER_NAME, smo8800);
 176         if (err) {
 177                 dev_err(&device->dev,
 178                         "failed to request thread for IRQ %d: %d\n",
 179                         smo8800->irq, err);
 180                 goto error;
 181         }
 182
 183         dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
 184                  smo8800->irq);
 185         return 0;
 186
 187 error:
 188         misc_deregister(&smo8800->miscdev);
 189         return err;
 190 }
 191
 192 static int smo8800_remove(struct acpi_device *device)
 193 {
 194         struct smo8800_device *smo8800 = device->driver_data;
 195
 196         free_irq(smo8800->irq, smo8800);
 197         misc_deregister(&smo8800->miscdev);
 198         dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
 199         return 0;
 200 }
 201
 202 /* NOTE: Keep this list in sync with drivers/i2c/busses/i2c-i801.c */
 203 static const struct acpi_device_id smo8800_ids[] = {
 204         { "SMO8800", 0 },
 205         { "SMO8801", 0 },
 206         { "SMO8810", 0 },
 207         { "SMO8811", 0 },
 208         { "SMO8820", 0 },
 209         { "SMO8821", 0 },
 210         { "SMO8830", 0 },
 211         { "SMO8831", 0 },
 212         { "", 0 },
 213 };
 214
 215 MODULE_DEVICE_TABLE(acpi, smo8800_ids);
 216
 217 static struct acpi_driver smo8800_driver = {
 218         .name = DRIVER_NAME,
 219         .class = "Latitude",
 220         .ids = smo8800_ids,
 221         .ops = {
 222                 .add = smo8800_add,
 223                 .remove = smo8800_remove,
 224         },
 225         .owner = THIS_MODULE,
 226 };
 227
 228 module_acpi_driver(smo8800_driver);
 229
 230 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
 231 MODULE_LICENSE("GPL");
 232 MODULE_AUTHOR("Sonal Santan, Pali Rohár");